Plural short sustain percussion gates and common gate arrangement for electronic musical instruments



United States Patent [72] inventor David A. Bunger Cincinnati, Ohio 211App]. No. 788,868 [22] Filed Jan. 3, 1969 [45] Patented Dec. 22, 1970[73] Assignee D. H. Baldwin Company Cincinnati, Ohio a corporation ofOhio [54] PLURAL SHORT SUSTAIN PERCUSSION GATES AND COMMON GATEARRANGEMENT FOR ELECTRONIC MUSICAL INSTRUMENTS 12 Claims, 7 DrawingFigs.

[52] U.S. Cl. 84/1.26, 84/1. 13 [51] Int. Cl Gl0h 1/02 [50] FieldofSearch 84/l.0l, 1.03. 1.04.1.11. 1.13, 1.19. 1.24.1.26(B,O)

[56] References Cited UNITED STATES PATENTS 3,039,347 6/1962 Krauss etal. 84/1.26 3,176,060 3/1965 Bissonette et al.... 84/l.01 3,391,2407/1968 Uetrecht 84/l.01

3,476,864 11/1969 Munchetal Primary Examiner--W. E. RayAttorneysHurvitz, Rose and Greene, W. H. Breunig and D.

H. Baldwin Co.

common gate. In addition, actuation of each key supplies tone signal toa fast-rise, fast-decay common gate, the output of which is paralleledto the output of the long sustain common gate, to provide the effect ofplucking a string. The individual short sustain gates simulate a dampedpercussive sound when a note is depressed and released immediately, andin that case the long sustain common gate will not affect the sound,although that gate will go through a cycle of operations. The fast-rise,fast-decay common gate will affect the sound regardless of whether anote is depressed and released or depressed and held down. If the key isdepressed and held down, the individual short sustain gate will remainon, but the common gate will modify the signal to provide a long sustainnote. The various percussive voices can be reiterated by applyingreiteration pulses to the common gates.

g5, T5 SR C \o be: KEY cl =7- 15 '2? 2 ,FLEIJER s pre a k SPIHZ SPERKER.li' 4 TRIGGER 18 53ml 1? 32 FlU'ZER an? RE-l'l' v osc. 33 wPATENIEDutczemm 3,549,779

sum 2 [IF 3 mEEaIF- H6 4 .ul 10K IOK D C GATE #1 i PlANO Is I #r)w ue 2DINVENTOR DAVID h. BUHGER ATTORNEYS PATENTEUHEE22|970 3549.779

sum MP 3' D CID S' l mq ole 39K [DH I MANDOLIN IINVENTOR DAVID A.BUhfiER ATTORNEYS PLURAL SHORT SUSTAIN PERCUSSION GATES AND COMMON GATEARRANGEMENT FOR ELECTRONIC MUSICAL INSTRUMENTS BACKGROUND OF THEINVENTION It is known, in the electronic organ art, to utilizepercussive gates for tone signals. These are essentially keyed on gateswhich have rather short sustain time, and they remain on so long as akey remains depressed. They provide percussive sounds if a key is hitand released at once.

Percussive gates are known to which tone signal is or may becontinuously applied, and which in response to a short control pulse,provided on key actuation, provide a rapid buildup and long decay ofconductivity. Such gates provide a long sustained note of predeterminedduration, which terminates even if the key which provided the controlpulse should be held down. However, the two types of gates have notheretofore been employed in cascade. When so employed, they provideexcellent piano simulation in that hitting and releasing a key quickly,i.e., staccato playing, provides a short sustained note, but actuating akey and maintaining it actuated, provides a long sustained note ofpredetermined duration, regardless of duration of key actuation.

In addition to the above, actuation of each key provides signal to apercussive gate which forms a waveform simulating the plucking of astring, and which is exclusive of the common gate. The several gates maybe respectively subjected to notes of different footages or frequencies,if desired, and reiteration can be accomplished by applying repetitiveshort pulses to the common gate, to simulate strumming. A variety ofpercussive voices can be simulated by means of the present gating systemand appropriate tone color filters.

SUMMARY OF THE INVENTION A percussive gating system employingtwo gatesin series, one of which is responsive to key actuation, a separate gatebeing provided for each key, and is a diode gate having a short sustain,the other of which is a common gate, i.e., common to all the shortsustain gates, and has a predetermined long duration conductivity. Thelatter comes into play only if a key is depressed for a sufficientlylong time. In addition, a common gate can be connected directly betweenthe tone sources and the output of the first mentioned common gate,which has a very short sustain and a fast rise, to simulate plucking ofstrings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a block diagram of a systemaccording to the invention;

FIG. 2 is a wave shape diagram indicating delay times through theseveral gates of FIG. 1;

FIG. 3 is a schematic circuit diagram of the trigger and pulse shaper,of FIG. 1;

FIG. 4 is a schematic circuit diagram of a portion of the system of FIG.1, arranged to simulate the piano;

FIG. 5 is a schematic circuit diagram of a portion of the system of FIG.1, arranged to simulate the banjo;

FIG. 6 is a schematic circuit diagram of a portion of the system of FIG.1, arranged to simulate the mandolin; and

FIG. 7 is a schematic circuit diagram of a portion of the system of FIG.1, arranged to simulate the marimba.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, 10, ll, 12 and9 are respectively tone sources of diverse frequencies f f f and frespectively. Connected in cascade with source 12 is a short sustaingate SPG This gate is connected to a header I3. Tone source 9 isconnected in cascade with gate SPG which in turn is connected to headerl3. Tone source.l0 is connected via key switch S, to a header 14, as insource 11 by means of key switch S Header 13 is connected via filter 15to a common gate 16; header 14 is connected via filter 17 to common gate18. Common gates 16 and 18 issueto a common collection point I9, whichcan be connected by a tab switch 20 to an amplifier 21 and loudspeaker22.

Associated with each of key switches S and S is another key switch S,,,,S respectively. The latter are ganged with switches S and 5;,respectively. Switches S and S are connected to a DC voltage line 25,which provides gating voltage to gates SPG and SPS The latter aretypical short sustain gates, employing two series diodes D D per gate,which are normally nonconductive of the tone supplied by sources 9 and12, but which are rendered conductive, on closure of a key switch as Sby the consequent application of gating voltage. The gate remainsconductive as long as gating voltage is applied. Since the gatingvoltage is applied across capacitor C this capacitor is charged, and onopening the key switch, discharges through the gate, sustainingconductivity for a sensible time. An appropriate decay curve isillustrated at D,,

FIG. 2. Resistance R controls the rise of conductivity, of the h SPGgate. If a key is depressed and rapidly released, the SPG gate willprovide an output signal which rises and then falls according to thecurve D,. If desired, the resistance R may be deleted and slowing ofrise time eliminated.

Whenever a key is depressed, and whether or not some other key isconcurrently depressed, a voltage pulse is sensed by trigger and pulseshaper 29, which is applied to gates 16 and 18, via line 30. These gatesare normally nonconductive, but in response to application of a controlpulse proceed through a predetermined cycle of conductivity, typicallythat of D of FIG. 2, for gate l6, and D of FIG. 2 for gate 18. Tonesignal is applied to gate 18 as soon as a key is depressed. To gate 16is applied the output of one or more percussive gates SPG.

It is within the scope of the invention to employ source 10 in place ofsource 12, if desired, or source 12 may be one or more octaves above orbelow source 10, in frequency, i.e., the tones may be of differentfootages, or other frequency relations may appeal musically to thedesigner.

Gates 16 and 18 are normally nonconductive, and are turned onconcurrently by pulses applied over line 30. Gate 18 produces a pulse oftone which rises very rapidly and decays very rapidly, regardless ofwhether the calling key is held down, per curve D The SPG gate producesa pulse of tone, per curve D,, if a key is depressed and rapidlyreleased, or it produces a steady tone if the key is held down. Gate 16produces a pulse per curve D which can only occur if a key is held down,since otherwise the pulse of tone supplied to the input of gate 16 is soshort that the gate has no audible effect, despite the fact that itproceeds through its normal cycle.

Reiteration pulses can be supplied to trigger and pulse shaper 29, viaswitch 32 from multivibrator oscillator 33. This has the effect ofrepeating the called-for tone or chord, so long as the appropriate keyor keys are depressed.

In FIG. 3 are illustrated key switches S one for each key of the organ,or for those keys to which the system is to apply. A voltage terminal 40supplies voltage via a resistance R, to the switches in parallel. Theswitches then proceed via resistances R to capacitors C,, which providea transient pulse whenever a key switch is closed, because this actionchanges the voltage drop in resistance R This voltage pulse actuates amonostable flip-flop 36, comprising transistors T and T to produce apulse of predetermined amplitude and duration. This pulse is inverted byamplifier 37, employing transistor T and applied to terminal B. Avoltage divider R R connected to the supply lead 38 for T T T all NPNtransistors, provides 2.8 at terminal '39, the utility of which will bedescribed hereinafter.

Theoutput of flip-flop 36 is also coupled to the input of PNP transistorT supplied from negative supply line 40, and a control pulse provided byT is applied to terminal A. A DC voltage of l2 is also provided byvoltage divider R R Reiteration voltage is supplied to the base of T,from terminal 42, via series RC circuit R C and diode D Resistance Rprovides charging path for capacitor C T is normally conductive, sinceits base is connected to the positive supply. On application of anegative pulse via R transistor T becomes nonconductive. T is normallynonconductive because its base is at when T is conductive. When Tbecomes nonconductive, T turns on, discharging C Q, then maintains Tnonconductive for a time after the control pulse disappears, and untilits charge dissipates. T is normally conductive, and on arrival of anegative pulse from T becomes transiently nonconductive, providing apositive pulse at terminal B.

The output of T which is a negative pulse, is differentiated in C R andturns on transistor T at PNP transistor. Point A at the output of T isnormally at 15, since T is normally nonconductive, its base beinggrounded for DC. When T is rendered transiently conductive, point T.goes to 0, but this output pulse is extremely short due to the action ofthe differentiator.

Referring now to FIG. 4 of the accompanying drawings, tone signal fromheader 13 is applied via active filter 15, which is tailored to simulatethe content of a piano tone. The output of active filter 15 is appliedto a generally conventional diode gate 16. Gate 16 includes a groundingresistance R at its input, and another R at its output. The gate itselfinvolves back-to-hack diodes D and D having their anodes coupled via acapacitor C which isolates the gates for DC, but permits AC signal topass. Gating voltage is applied to the anodes of D D via lm resistancesR R so that gating current is measurable in microamperes.

Input current is constrained to have a low value. For these operatingconditions, the gate is linear over its entire range of gated signal,producing no harmonic or intermodulation distortion, despite the factthat the input signal is complex and that the gating voltage proceedsthrough a wide range of values. The gate per se forms the subject matterof a copending application, filed on Nov. 13, 1968, in the name ofHarris, entitled Touch Percussion for Electronic Organ, and assigned tothe assignee of this present application.

Gating voltage is applied at terminal B, being taken from terminal B ofFIG. 3. The gating voltage is applied via diode D to charge capacitor Cand C Resistance R provides a charging time constant for C The charge isapplied as a short pulse, and cannot leak off via D but only slowly viaresistance R and T (FIG. 4). Diode D acts as a snubber, being conductiveso long as the gating voltage sufficiently ex ceeds a 2.8 bias set in atterminal 50, and thereafter being nonconductive. A gating pulse appliedto charge C and C then decays via three paths, i.e., R R and R and via DR for a time. When the gating voltage has decayed to 2.8, the diode Dshuts off, and decay continues only via R R R and hence at a slowerrate. This double rate of decay of gating voltage is desirable tosimulate piano tones.

The gate 18 employs a PET, F Tone signal is applied via passive highpass filter 17, to the source electrode and the drain electrode proceedsto one side of tab switch 20. The gate electrode is connected viaresistance R to l2 and also to a point A via D It will be recalled thatpoint A is normally at and proceeds to ground potential on receipt of acontrol pulse. The l 5 is not applied because diode D is interposed, andthe gate is held nonconductive by the l2 bias. Upon grounding of pointA, the negative charge on C rapidly decays via D Capacitor C andresistance R provide a click filter. The time constant of C R nowcontrols rise time, since T is only momentarily conductive. Thedischarge of C takes place via D T and is very rapid; the recharge takesplace through R and is slower, and the total wave shape is that ofD FIG.2.

The system of FIG. 4 reproduces the sound of a piano hammer striking astring, followed by a rapid building of tone, followed by a slow decay,if the key is held down, and the double-rate decay requisite for truepiano reproduction. If the key is struck and promptly released, gate 16is ineffective because the SPG gate has a far more rapid decay time andabout the same rise curve, as does gate 16. Gate 16 goes through itscycle of operations, for each depression of a key, regardless of howlong the key is held depressed, but it produces no audible effect if thekey is released with sufiicient rapidity.

The system of the invention is commonly applicable to simulation of thetones of the piano, the banjo, and the mandolin, although filtering andtime constants differ for the separate cases. Appropriate circuitry,with circuit values and input wave characteristics, are provided inFIGS. 4, S, 6, 7, respectively. To simulate the marimba, the circuit ofFIG. 7 is adequate, i.e., use of gate 18, alone.

For the case of the piano, signal input for gate 16 is derived from astring percussion filter amplifier, while the gate 18 is supplied withsolo 8-foot square waves. For the case of the banjo, both gates aresupplied via a common low-pass active filter 6t), and the utilization ofa separate tone source for gate 18 is dispensed with. The net responseof the system is then the sum of curves D and D,, or D and D,, as in thecase of the piano, but the summed tones are duplicate in the case of thebanjo, but not in the case of the piano.

In the case of the mandolin, the input filters are high pass filters,for both gates 16 and 113. Gate 16 receives output from a percussivestring filter amplifier, but gate 18 and filter 71, receive solo 8-foottriangular waves.

In the case of the marimba, the filter 16 is not employed, since thetones are short. The gate 18 alone suffices, with a low pass filter 72at its input, to which is applied a l-foot square wave, a 26-foot squarewave being applied through a high pass filter to the input PET, and theoutput of a vibra harp percussive amplifier to the output of the FET. Inthis case, the vibra harp component of the output is always of durationestablished by an SPG gate, which is provided.

Iclaim:

1. An organ system, comprising:

a plurality of tone signal sources;

plural relatively short percussive gates connected in cascade one forone with said tone signal sources;

key operated means for rendering said gates selectively conductive, eachof said gates being arranged to remain conductive while one associatedkey is actuated and to become gradually nonconductive thereafter with arelatively short sustain; and

a long sustain gate connected commonly in cascade with all said shortpercussive gates, said long sustain gate being arranged to be responsiveto actuation of one of said keys for initiating a gating cycle ofpredetermined duration regardless of the actuated condition of saidassociated key.

2. An organ system, comprising:

a plurality of tone signal sources;

a plurality of key switches;

means responsive to selective actuation of said key switches forselectively calling forth tone signals from said tone signal sources;

a long sustain common gate;

a load; and

means connecting said common gate to pass all said tone signals to saidload, said common gate being arranged to be responsive to operation ofany of said key switches for initiating an on-gating cycle ofpredetermined duration and wave shape regardless of the duration ofactuation of said any of said key switches.

3. The combination according to claim 2, wherein said common gate isoperative to initiate said gating cycle in response to triggeringpulses, and wherein is provided means responsive to actuation of any ofsaid key switches regardless of the then condition of the remaining keyswitches, actuated or unactuated, for generating one of said triggeringpulses.

4. The combination according to claim 2, wherein the first mentionedmeans are short sustain gates individual to said tone signal sources.

5. The combination according to claim 4, wherein is further provided afurther common gate having sustain time shorter than the sustain timesof said short sustain gates, means for connecting said further gateselectively between said tone signal sources and said load, said furthercommon gate having a faster build up time than said short sustain gateshave.

6. The combination according to claim 4, wherein said short sustaingates and said common gate have substantially the same buildups, butradically different decay characteristics.

7. The combination according to claim 6, wherein said common gate has adouble-rate decay characteristic.

8. The combination according to claim 7, wherein is further provided atone color filter connected antecedent to said common gate, and whereinsaid common gate is a linear gate.

9. The combination according to claim 5, wherein said common gate is alinear gate and wherein said further common gate is a FET gate, saidtone signals being square wave signals, means directly applying saidsquare wave signals for passage by said FET gate, and tone colorfiltering circuitry connected between said tone signal sources and saidcommon gate.

10. The combination according to claim 2, wherein is further provided areiteration signal source, and means apply ing said reiteration signalsto initiate gating cycles of said common gate.

11. The combination according to claim 3, wherein is further provided areiteration signal source, and means responsive to said reiterationsignal source for supply said triggering pulses.

12. In a gating system for an electronic musical instrument:

a source of tone signal;

a normally open switch;

a load;

means responsive to closure of said switch for transferring tone signalfrom said source in a path toward said load for the duration of saidclosure;

a gate connected in the path of said tone signal antecedent to saidload, said gate being responsive to a control signal to providing apredetermined conductivity pattern as a function of time; and

means responsive to each initiation of closure of said switch forinitiating said pattern, whereby a sufficiently long duration closure ofsaid switch produces a tone signal conforming to said pattern in toto,but a sufficiently short duration closure of said switch produces acorrespondingly short tone signal conforming to said pattern only inpart.

